Which statement relates to Bernoulli's principle?
For every action there is an equal and opposite reaction.
An additional upward force is generated as the lower surface of the airfoil deflects air downward.
Air traveling faster over the curved upper surface of an airfoil causes lower pressure on the top surface.✓ Correct Answer
Explanation
Bernoulli's principle says that as the velocity of a moving fluid increases, its pressure decreases (PHAK Ch. 4). Air flowing faster over the curved upper surface of the wing therefore has lower pressure than the air below, and that pressure difference produces lift. The action/reaction statement is Newton's third law, and the downward deflection of air by the lower surface is also a Newtonian explanation of lift, not Bernoulli's principle.
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